Expected and Unexpected Features of the Newly Discovered Bat Influenza A-like Viruses

Ma, Wenjun; García-Sastre, Adolfo; Schwemmle, Martin

Consistent with the observation that bat influenza A-like HL17 and HL18 do not bind to canonical sialic acid receptors, bat NAs lack detectable neuraminidase activity [6] . Although the overall N10 structure is similar to other known influenza NA structures, the region corresponding to the highly conserved active site in the N1-N9 subtypes is substantially different [6, 7] . The structural features and the fact that the recombinant N10 protein exhibits no or extremely low NA activity suggests that it may have a different function than the NA proteins of other influenza viruses. We therefore suggest that N10 and N11 from bat influenza A-like viruses should be designated as "NA-like" (NL) proteins (NL10 and NL11). Furthermore, the current classification of bat influenza A-like viruses "H17N10 and H18N11" is misleading and should be reconsidered; we suggest that they can be designated as "HL17NL10 and HL18NL11". At this moment, it is even unclear whether the receptor binding protein is the HL or the NL protein.